The present invention relates generally to aircraft engines, and, more specifically, to thrust reversers therein.
A typical turbofan aircraft engine includes a fan powered by a core engine for producing propulsion thrust for powering the aircraft in flight. The core engine typically has in serial flow communication a multistage axial compressor, annular combustor, and high pressure turbine joined to the compressor by one shaft. A second shaft joins the fan to a low pressure turbine disposed downstream from the high pressure turbine.
The engine also includes a fan nacelle surrounding the cowling or nacelle of the core engine which defines an annular bypass duct therebetween. The nacelle may be short and terminates in a fan outlet nozzle surrounding the core engine upstream from an independent core exhaust nozzle at the downstream end thereof. Or, the fan nacelle may be long and extends downstream past the core nozzle for collectively discharging both the fan bypass air and the core exhaust in a common exhaust nozzle disposed downstream therefrom.
The turbofan engine typically also includes a fan thrust reverser for providing aerodynamic braking during aircraft landing on a runway. Various types of fan thrust reversers are known in the art, one of which includes pivoting doors that block the aft travel of the fan air in the bypass duct and redirect it in the forward direction for reversing the direction of fan air thrust.
The known fan reversers have various advantages and various disadvantages relating to complexity, size, weight, and cost. And, the pivoting door fan reverser requires redundant locking or latching devices for preventing inadvertent in-flight deployment thereof.
In a large turbofan engine, there may be four pivoting doors spaced around the nacelle, with each of those four doors requiring three independent latches for satisfying government certification requirements. Accordingly, twelve independent latches would be required for the entire fan reverser, and correspondingly increase the complexity and cost of the reverser system and its control.
U.S. patent application Ser. No. 10/679,882; filed Oct. 6, 2003, and assigned to the present assignee, discloses an improved bifold door thrust reverser having many advantages over typical fan thrust reversers. The bifold door reverser includes outer and inner doors which are deployed in opposition for blocking and turning the fan bypass flow during thrust reverse operation. A gang of the outer doors may be deployed in unison with a common inner door, all deployed using a common actuator.
The outer and inner doors maintain continuity of the outer and inner skins of the nacelle when stowed, and the actuation mechanism is fully contained in the nacelle between the two skins. The bifold door reverser is relatively compact and requires relatively small stroke of the actuators used therein.
And, the compact and nested configuration of the outer and inner doors in the bifold door reverser permit therein the introduction of a new locking or latching system as further described hereinbelow.